The present invention relates to a valve device for controlling the filling level of cylinders and the like with liquefied gases.
U.S. patent application Ser. No. 09/047.511 discloses a valve device for controlling the level to which cylinders and the like are filled with liquefied gases. The device is substantially constituted by an upper connecting body which can be coupled to a cylinder for liquefied gases and forms a tubular gas infeed element which ends with a coupling body which can be coupled to a lower connecting body, so as to retain an elastic membrane for closing the openings arranged on the coupling body outside the tubular body.
The membrane, which has through holes, connects the tubular element to a chamber inside which a valve control element is provided which is controlled by a float element, which is provided with an actuation cam for the control element, which is meant to let the control element descend, when the cylinder has been filled to the intended level, so as to close the chamber, so that the counterpressure generated inside the chamber pushes the membrane hermetically against the tubular element in order to close the openings for feeding gas toward the inside of the cylinder.
In this embodiment, it is important for the coupling between the upper connecting body and the lower connecting body to be produced with an excellent seal and with the possibility of clamping the peripheral region of the membrane in order to retain it in position.
In the embodiments of the prior art, the coupling is normally performed by heat-sealing or gluing. The effectiveness of these processes is not easy to control and therefore it is not possible to be absolutely certain of a complete and durable clamping action on the edge of the membrane, which if not firmly retained in its peripheral region can create seepage regions, with consequent failure of the valve device.